Effect of NPK fertilizer and interval management on the chemical properties of coastal plain sands of Akpabuyo, Nigeria

Investigation of the chemical properties of the coastal plain soils treated with NPK 20:10:10 fertilizer (NPK) at the rate of 0,60, 90 and 120kg ha -1 ) and observed at intervals of 3,6,9 and 12 months was carried out from March 2009 to 2010 at Akpabuyo, Cross River State, Nigeria. The experiment comprises of four fertilizer rates and four management intervals fitted into a Latin square design. The soils pH value increased consistently from 3 to 12months. Mean values of organic matter decreased with increase in profile depth from 2.12-1.34g kg -1 ). The distribution of N from the top soil down the profile increased consistently from 3 to 12 months. The mean value of N from the top soil was 0.82%. Exceeding 0.2%, the critical value and was more than the mean values obtained in the sub-surface soil. The mean value of P (33 mgkg -1 )) during the 9 months interval was significantly (P 0.5cmol kg -1 )), low contents of K and Na as well as high exchangeable Al. levels (> 4.0 cmol kg -1 )) and cation exchange capacity (22 – 36 cmol kg -1 )) The application of 90 kg/ha -1 ) NPK fertilizer during the 9 months interval gave highest values of N.P, Ca and Mg under the condition of the experiment, indicating that these elements will not be deficient in these soils. Equally, the CEC, organic matter and base saturation had their advantage in the 9 months interval where 90 kg'' was applied. This is cost effective and could be used to improve crop production in Akpabuyo, Nigeria. KEY WORD : Chemical Properties, NPK Fertilization, Management Intervals, Coastal Plain Sands.